Plug fuse



Dec- 4, 1934 .1. G. RIESMAN i PLUG FUSE Filed Sep. 22, 1932 'IVI @stemma clamor-13o) 'Imis-invention: relates-to felectrio `fuses `of the plug typewandfgmore^ particularly to; `a fuse.l `provided with afglassor-.similar transparent top such asis I,shown in .theBaenzigen ReissuefPatent No. 17,34ltgranted June:-25, `1929. ,.Qne f of the objects of-1 .this rinvention'isgtofinorease thev-isibility .fuse element. so :thatiablown-tuse.. is,more

readily Y detected.

i, Further .objects are; to :decrease the amount of fuse material consumedain -.-.the,b1owing.,of the. fuse. to. thereby. fdecrease .the amount of hot vlgas .formed ,and theC pressurewthin ,thel fuse body, and to provide a body of f air atatmospheric temperaturewith which thehotgases areimmediatelydlluted thus toreducethe ,temperature o1'-` any gases' whichj mayivent from' withinl the plug-'andto causesuch* gases as do vent'to -be relatively-cool so *that safty'f fromrire5k hazard is assured even under the most adverseweondtionsi Pbr'=a=more complete-understanding of this invention, reference may be had to the accompanying drawing in which Figure 1 is a central cross section through a plug fuse embodying this invention.

Figure 2 is a top plan of the same.

Figure 3 is a section on line 3-3 of Figure 1.

Figures 4 and 5 are perspectives of certain parts of the device.

Referring to the drawing, at 1 is shown a base of insulating material having a terminal 2 extending therethrough, this terminal being positioned to engage the usual central terminal of a threaded socket to receive the plug fuse. This base is shown as provided above its lower end with an outwardly extending ange 3 on which engages the end portion of a tubular wall 4 of a body portion 5 of the fuse whichas shown is of transparent insulating material such as lglass and which is provided with a window at 6 opposite to the terminal 2. The body portion and the base are shown as held together by a threaded conductive sleeve 7 which may be screwed into the threaded receiving socket. This sleeve is preferably made of sheet material with the threads rolled therein and engages a suitably threaded outer face of the wall 4 and is provided with an in-turned ange 8 at its lower end which engages beneath the flange 3 and thus retains the body and base assembled. A fuse element 10 is secured at one end to the terminal 2 as by being embedded in a plug 11 of solder or the like flowed into the hollow upper end of the terminal 2 and this fuse element is brought upwardly toward the window 6 at one side of the wall 4 and is then brought across the tubular wall member substantial-ly:diametricallyt 35,-; Shown at 12,-

`then turned bar :kwardly i and gdownwardly and ;.pas ses.outbetweexrthe lower end of: the ywall -4-iamdft-he flanged, 11ndJ is ftbenturned? upwardly andaunited-to-theshell 7 asbysolder-at 14. v

In order that the hot gases from the fusegtwhen blown may be prevented from impingingdrectly .against` Ithe;vvall,\4-remote from, the. Vtop of the por-tion a` protecting; sleeve fof, `insulating v-materialsucht as paper orthez like,.as 'at-,15,is ,positioned inwardly of 1 andt substantially? against the wall.V 4i and between. itiand` the vfuse Eelement `10. 'llhis sleeve Vis-shownfas?resting against `the .top facefoi thebase flange 1 3- and r"outwarqzlly of. a aneef upstandins-Irom 'thabese 1- 4 t A; Substantiallyfmidway ofI rtherlportion, 12of,the friser-:element :iti-isforme@ of. l`reducedcross section wat 2.1;, t0; :localize .they blowing 0f fthe. fuse where.. .Caribe readlyfrseenathrushcthe Window 6; andiustruckfof iliisspfxr-tien4 this; let-:element is underlaid by a relatively flimsy sheet material disk 25 of paper or the like which acts as a partition normally dividing the space enclosed by the body and base into two non-communicative compartments or chambers 26 and 2'7. The portion 21 s,

readily be dislodged from its normal position on es the relatively narrow edge of the sleeve 15 and to Vthis end it is shown as resting on the top edge of the sleeve 15 and supported by the fuse element 10, preferably being provided with opposed notches 28 and 29 through which the fuse element passes, the fuse element being bent inwardly just beneath the element 25 suiiiciently to normally support it in proper position. This partition element 25 denes a relatively small space within which that portion of the fuse element which vaporizes when the fuse blows is positioned and it thus limits the amount of oxygen available for combustion at the instant the fuse blows so that the amount of metal vaporized when this occurs is substantially reduced.

The pressure produced in this small chamber 26 when the `fuse blows is suicient to dislodge the disk 25 which is blown back into the chamber 27, as shown in dotted lines in Figure l, so that the air Within the chamber 27 is immediately available after the actual combustion ceases to cool the gaseous combustion products formed in the chamber 26, thus to reduce the pressure of gases within the fuse body. Moreover, these gases may vent from the body through the joint between the body, the base, and the external shell and the gases which thus escape are composed largely of the air normally within the chamber 27, this being relatively cool so that the gases which are vented are of low temperature and cannot produce a tire risk. The upper portion or the body 5 surrounding the window 6 is of relatively thick material and is fully able to withstand the momentary action of the hot gases thereon without danger of cracking, while the lower end of the body at the wall 4 is fully protected fromV the impingement of the hot gases thereon bythe sleeve 15 and the disk' 25. This disk 25 also tends to hold the fuse in position immediately in back of the window and may be oi.' a colorto increase the visibility oi' the fuse element andthusbe oi material aid in detecting a blown fuse. It may also have printed thereon suitable marks indicating the capacity o! the fuse readily visible through the window 6. v

From the foregoing description ofy an embodiment ofvthis invention it should be-evident to those skilled in the art thatvarious changes and modiiications may be 'made without departing from its spirit or scope as denned by the appended claims. t

,1. -A fuse having' a non-conductive base provided with a terminal, a transparent body portion having a window opposite to said base, and a side wall extending theretoward, a threaded conductive shellv enclosing said side wall, a fuse element having its opposite ends secured to said terminal and shell, respectively, and having an intermediate portion of `reduced, cross section back of said window,'a protecting sleeve inwardly of and substantially' against said side wall and between said wall and said fuse element and presenting a relatively narrow edge, and a relatively imsy sheet material member positioned back of said intermediate fuse element portion and adje.- cent thereto and forming a partition normally dividing the space enclosed by said body and base into a pair of chambers in one of which said reduced cross sectional fuse portion lies, said sheet material member being supported on said edge tree to give way under pressure produced when the fuse element blows, to unite said chambers.

2. A fuse having a non-conductive base provided with a terminal, a transparent body portion having a window opposite to said base and a side wall extending theretoward, a threaded conductive shell enclosing said side wall and having a portieriengagingisairll base and holding said basey and body portionl assembled, a fuse element having vits opposite ends secured to said terminal and shell, respectively, and having an intermediate portion of reduced cross section back of said window, a protecting sleeve within and substantially against said side wall and between said wall and said fuseelement, and a sheet material member positioned back of said intermediate fuse element portion and adjacent thereto and to one end of said sleeve and lforming a partition normally dividing the space enclosed by said body and baseint'o a pair of non-communicating chambers 'in one of which said reduced cross section fuse portion lies and the other of which is vented to the atmosphere through the joint between said body portionbase and shell. n v

3. `A fuse comprising members detlning a space, a partition normally dividing said space into non-communicating compartments, means fior venting one of said compartments, a fuse element having a blowing portion in the other of'said compartments, and means for supporting :said W- titionto give way under-pressure produced when said fuse element blows.

JOSEPH 15 

